JP4882414B2 - Inspection method and inspection apparatus for hollow fiber membrane module - Google Patents

Description

The present invention relates to a hollow fiber membrane module inspection apparatus and a hollow fiber membrane module inspection method that can be used in an artificial dialysis machine, a sewage treatment apparatus, a water purifier, and the like, or a method of manufacturing a hollow fiber membrane module.

  As is well known, for example, a hollow fiber membrane module accommodates a yarn bundle of a hollow fiber membrane (hollow semipermeable membrane) having both ends opened in a container having both ends or one end opened, The gap between the container and the hollow fiber membrane is sealed with resin at both ends. Sealing with resin is performed by pouring resin into the space between the container and the yarn bundle (potting) and allowing the potting resin to permeate the space around each hollow fiber membrane in the case. The potting resin may enter the inside of the membrane, or the hollow fiber membrane may be crushed for some reason to be blocked. The blocked hollow fiber membrane becomes a so-called non-threaded thread, but if such a threaded thread is present, for example, in the case of an artificial dialyzer, blood that has flowed into the hollow fiber membrane remains in the hollow fiber membrane, and the dialysis performance If it is remarkable, sufficient artificial dialysis cannot be performed. For this reason, it is necessary to remove a hollow fiber membrane module in which a certain number or more of unthreaded yarns are present as defective products from the production line.

  Conventionally, the quality of a hollow fiber membrane module that is related to the occurrence of thread breakage is determined by irradiating the end surfaces of the potting resin at both ends of the hollow fiber membrane module (hereinafter referred to as potting end surfaces) with incident light, and scattering at the end surfaces. A method in which light is picked up by a CCD camera, the average value of the brightness of the hollow portion of the hollow fiber membrane is obtained from the picked-up image, and if the brightness average value is higher than a predetermined threshold value, the inspection is performed by determining that there is no thread Is known (see, for example, Patent Document 1).

  Here, when the potting end face is warped or inclined and the angle of the reflected light changes (see the right side of FIG. 10), the angle of the reflected light changes when normal light is used as the light source of the irradiation light. In some cases, the image pickup device cannot receive light, and it is impossible to accurately determine a thread breakage.

  Therefore, in Patent Document 1, even when the potting end face has a warp or an inclination and the angle of the reflected light changes (see the right side of FIG. 10) by using ultraviolet rays as irradiation light, scattered light is It has been disclosed that it is possible to accurately determine the non-threading by taking an image.

However, since the hollow fiber membrane module irradiated with ultraviolet rays is yellowed and deteriorated by a well-known photochemical reaction by ultraviolet rays, the hollow fiber membrane module could not be inspected without deteriorating. Further, even when scattered light is received, there is a limit to the accuracy of the determination of non-threading.
JP 2004-113894 A

  The object of the present invention is to determine the presence / absence of a non-threading defect in a hollow fiber membrane module and the degree of its occurrence by a non-contact method without deteriorating the hollow fiber membrane module. It is an object of the present invention to provide a method and apparatus that can be performed more accurately than the method.

In order to achieve the above object, the present invention irradiates a potting end surface of a hollow fiber membrane module with light from a planar light source that satisfies the following condition (3) , images reflected light from the end surface, A hollow fiber membrane in which a hollow portion is hollow is detected by correlating an image obtained by the imaging with a predetermined model image, and the number of the hollow fiber membranes confirmed by the detection is a predetermined hollow If below the fiber membrane number threshold, provides a test how the hollow fiber membrane module, characterized in that determining the hollow fiber membrane module to be defective.
θ: Warping or inclination angle of potting end face of hollow fiber membrane module
H: Vertical and horizontal dimensions of flat light source (mm)
D: Distance (mm) between the optical axis center of the planar light source and the potting end surface of the hollow fiber membrane module
Here, in the present invention, with respect to the hollow portion, “being hollow” or “being hollow” means that there is no specific standard for how much the blockage by the resin is, and according to the inspection method of the present invention. It is determined by the relationship with a predetermined model image, in other words, it is arbitrarily set. At this time, the model image is a model image of a hollow fiber membrane having a hollow portion in a hollow state, and a region corresponding to the model image centered on a pixel group of the model image and each pixel of the image obtained by the imaging It is preferable that the hollow part is detected as a hollow fiber membrane in a hollow state when the correlation calculated by the normalized correlation with the pixel group in the image having the above is higher than a predetermined correlation threshold.

Also, the present invention is, in order to achieve the above object, a means for irradiating light from a planar light source that meets the following potting end faces of the hollow fiber membrane module (4) conditions, reflected from the end face Means for imaging light; means for detecting a hollow fiber membrane in which a hollow portion is in a hollow state by correlating an image obtained by the imaging with a predetermined model image; and the hollow fiber membrane confirmed by the detection A hollow fiber membrane module inspection device is provided that includes means for determining a hollow fiber membrane module as a defective product when the number of hollow fiber membranes is below a predetermined hollow fiber membrane number threshold.
θ: Warping or inclination angle of potting end face of hollow fiber membrane module
H: Vertical and horizontal dimensions of flat light source (mm)
D: Distance (mm) between the optical axis center of the planar light source and the potting end surface of the hollow fiber membrane module

According to the hollow fiber membrane module inspection apparatus, the hollow fiber membrane module inspection method, or the hollow fiber membrane module manufacturing method according to the present invention, the following various effects can be obtained.
(1) When the potting end face is warped or inclined, the hollow fiber membrane module is deteriorated because it is possible to accurately determine whether or not the hollow fiber membrane module is threaded without using ultraviolet rays as irradiation light. It is possible to inspect without making it.
(2) By using the normalized correlation as a means for comparing the captured image and the model image, it is possible to detect the presence / absence of a thread breakage defect in units of one line.
(3) By detecting the average value and standard deviation of the brightness of the captured image based on the upper limit or lower limit threshold value, the presence or absence of a thread defect is accurately detected without being affected by scratches or irregularities on the potting end face. Can do.
(4) Since the hollow fiber membrane module is selected based on the determination result, it is possible to prevent the outflow of defective products and improve the productivity.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration of a hollow fiber membrane module inspection apparatus according to an embodiment of the present invention. In FIG. 1, M is a hollow fiber membrane module, 1 is a module transfer device, 2 is a module support device, 3 is a light irradiation device, 4 is an imaging device, 5 is a hollow fiber membrane detection device, 6 is a defect determination device, 7 Indicates an operation command device, 8 indicates a display device, and 9 indicates a module discharge device. In this embodiment, the hollow fiber membrane modules M are inspected one by one. However, a plurality of hollow fiber membrane modules M may be mounted and inspected simultaneously.
Hereinafter, the configuration of each of these units will be described in detail together with the operation thereof.
<Module transfer device>
The module transfer device 1 is for mounting the hollow fiber membrane module M transferred from the previous process on a module support device 2 described later.
<Module support device>
The module support device 2 supports the hollow fiber membrane module M placed by the transfer device 1. Note that the position of the potting end face may be adjusted by a stopper jig in order to keep the distance between the potting end face of the hollow fiber membrane module M and the imaging device 4 described later constant. Further, a distance measuring device is installed to measure the distance between the potting end surface and the length measuring device, and a slider provided at the lower part of the imaging device 4 described later is moved back and forth in the optical axis direction so that the distance between the potting end surface and the imaging device 4 is increased. A method of keeping a certain distance may be used. In this embodiment, since a line sensor camera is used for the imaging device 4 described later, the hollow fiber membrane module M placed on the module support mechanism 2a is horizontally moved at a predetermined speed by the module scanning mechanism 2b. It can be moved.
<Light irradiation device>
The light irradiation device 3 includes a light source 3a and a power source 3b. In the present invention, the light source 3a is a planar light source. In this embodiment, a planar light source that emits white light from a halogen lamp is used as the light source 3a. Here, the planar light source is also referred to as a planar light source, and generally includes a planar light source and a light source that is regarded as a planar light source. The light emitting surface is a point light source such as an LED or a light bulb or a rod-shaped fluorescent lamp. This includes a light source having a planar shape having a two-dimensional extension different from the linear line light source having a one-dimensional extension. However, even if the shape of the light source itself is not a flat type but a dot or line shape, the light source itself includes one having a structure in which light is irradiated in a flat shape by means such as a diffusion plate. More specifically, it is sufficient if the entire potting end face of the hollow fiber membrane module to be measured can irradiate light in a planar shape so that the reflected light can be imaged. Those having light diffusing means are generally preferable, and the length or diameter of one side is about 2 to 3 times the length or diameter of one side of the potting end face, specifically, the length of one side of the potting end face. Or when a diameter is 45 mm, it is more preferable that it is a light source which has a shape of about 90-135 mm. As the light diffusing means, means for obtaining diffused light by transmitting the light irradiated to the sheet-like material and means for obtaining diffused light by reflecting the light irradiated to the sheet-like material are preferable. Then, the incident angle θi of the incident light from the light source 3a with respect to the potting end face of the module M and the reflection angle θo of the reflected light from the potting end face of the module M with respect to the imaging device 4 described later are equal to each other from the potting end face. Getting reflected light. Note that if the potting end face of the hollow fiber membrane module M has a warp or an inclination of an angle θ (see FIG. 10 for the angle θ), the direction of the specularly reflected light is a direction having an angle of θi−2θ. When the above-described light source having a one-dimensional spread is used, as shown on the left side of FIG. 10, the regularly reflected light may not be received by the imaging device 4 described later. Since such a part is imaged in a dark state, it becomes a factor of erroneous detection or oversight by a hollow fiber membrane detection device to be described later.

  However, in the embodiment using a planar light source having a two-dimensional extension, as shown on the right side of FIG. 10, incident oblique light having an angle of θi + 2θ with respect to the potting end surface having the warp or inclination of the angle θ. Since it is possible to irradiate, regular reflection light can be received by an imaging device 4 (described later) installed at the reflection angle θo. At this time, when the dimension of the planar light source is H in both length and width, and the distance between the optical axis center position of the planar light source and the potting end surface of the hollow fiber membrane module is D, the angle θ due to warp or inclination that can be received. The range is obtained by Equation 1 shown in FIG.

  In this embodiment, θ is ± 10 (°), but H is 90 (mm) and D is 110 (mm), so the allowable range of θ is −10 (°) to 10 (°). Thus, even when the hollow fiber membrane module M is warped or inclined at the potting end face, the irradiation light from the light source 3a can be received by the imaging device 4 to be described later, and oversight and erroneous detection can be prevented. .

The power source 3b turns on and off the light source 3a and adjusts the amount of light according to a command from an operation command device 7 described later.
<Imaging device>
The imaging device 4 is for obtaining an image by imaging the potting end face of the hollow fiber membrane module M on the module support device 2. In this embodiment, a line sensor camera having 2048 pixels is used.

Further, in this embodiment, the potting end surface of the hollow fiber membrane module M shown in FIG. 3 has a flat resin portion 10 with high brightness, a hollow fiber membrane portion 11 and a normal hollow fiber membrane that is a hollow. The hollow portion 12 is imaged with low luminance. In addition, since the hollow portion 13 is clogged with resin, the non-thread thread defect is imaged with high brightness in the same manner as the resin portion 10.
<Hollow fiber membrane detector>
The hollow fiber membrane detection device 5 detects the hollow fiber membrane in which the hollow portion 12 is hollow by correlating the captured image obtained by the imaging device 4 with a predetermined model image, and measures the number of the hollow fiber membranes. . The flow of processing of the hollow fiber membrane detection device 5 is as shown in FIG.

  In FIG. 4, a method for correlating an image obtained by the imaging device 4 with a predetermined model image is a model image pixel group created in advance using a hollow fiber membrane having a hollow portion as a model. The correlation degree R calculated by the normalized correlation with the pixel group in the captured image having an area corresponding to the model image centered on each pixel of the image obtained by imaging is a predetermined correlation threshold Rt If it is higher, it is detected as a hollow fiber membrane. Here, the normalized correlation is obtained by normalizing the degree of correlation with the magnitude of the luminance value of the input image. When the pixel group of the model image is f and the pixel group of the captured image is g, the correlation degree R can be obtained by Expression 2 shown in FIG. There are a correlation method, a vector correlation method, and the like as methods for obtaining the correlation, but a normalized correlation method that can absorb a change in luminance of the captured image due to a change in the light source 3a and has high resistance to noise is desirable.

  In addition, the detected hollow fiber membrane group may include a flaw 13 on the potting end face as shown in FIG. 6 that is imaged with lower brightness than a flat potting portion. When these are added to the number of hollow fiber membranes, the number of normal hollow fiber membranes is counted more than the actual number, so there is a possibility that the hollow fiber membrane module M which is actually a defective product is erroneously determined as a good product. Therefore, for the hollow fiber membrane candidate whose calculated correlation degree R is higher than a predetermined correlation degree threshold value Rt, a pixel in the captured image having a region corresponding to a model image centered on the hollow fiber membrane candidate coordinates By extracting only those in which the average luminance value A of the group is within the range between the upper limit threshold value Atu and the lower limit threshold value Atl, it is possible to prevent false detection of a flaw 13 or the like that is brightly imaged as compared with the normal yarn portion as a normal yarn. To do.

In addition, the detected hollow fiber membrane group may include irregularities 14 due to poor potting as shown in FIG. 7, which are captured with lower luminance than a flat potting portion. If this is added to the number of hollow fiber membranes, the number of normal hollow fiber membranes is counted more than the actual number, so there is a possibility that the hollow fiber membrane module M that is actually a defective product is erroneously determined as a good product. Therefore, for the hollow fiber membrane candidate whose calculated correlation degree R is higher than a predetermined correlation degree threshold value Rt, a pixel in the captured image having a region corresponding to a model image centered on the hollow fiber membrane candidate coordinates By confirming that the brightness standard deviation σ of the group is within the range of the predetermined upper limit threshold σtu and the lower limit threshold σtl, an image is captured as dark as the normal yarn portion, but the area is larger than that of the hollow fiber membrane Thus, it is possible to prevent erroneous detection in which the unevenness 14 on the potting end face having a flat luminance distribution and a small luminance standard deviation is detected as a normal thread.
<Defect determination device>
The defect determination device 6 compares the hollow fiber membrane number N in the hollow state obtained by the hollow fiber membrane detection device 5 with a predetermined hollow fiber membrane number threshold value Nt, and the hollow fiber membrane number N falls below the threshold value Nt. For example, the hollow fiber membrane module M is determined as a defective product. The processing flow of the defect determination device 6 is as shown in FIG.
<Operation command device>
The operation command device 7 responds to differences in the outer diameter of the hollow fiber membrane module M to be measured, the outer diameter and inner diameter of the hollow fiber membrane, the assembly method of the module, etc., and commands the hollow fiber membrane detection device 5 and the defect determination device 6. Model image suitable for the hollow fiber membrane module M, correlation threshold Rt, luminance average upper limit threshold Atu, luminance average lower limit threshold Atl, luminance standard deviation upper threshold σtu, luminance standard deviation lower threshold σtl, hollow fiber membrane While setting the detection number threshold value Nt, a command is sent to the power source 3b of the light irradiation device, and the light source 3a is turned on / off and the amount of light is adjusted. In addition, a command is sent to the module support device 2 so that the movement of the hollow fiber membrane module M is performed at a speed suitable for imaging by the imaging device 4.
<Display device>
The display device 8 is used for displaying the inspection result and displaying an image in which the mark 15 is plotted on the normal yarn portion.
<Module ejector>
The module discharge device 9 discharges only the good hollow fiber membrane module M to the next process according to the determination by the defect determination device 6.

  The method for producing a hollow fiber module according to the present invention includes a step of inspecting the end face using the above inspection method, and is excellent in production efficiency by eliminating defective products by the above inspection. The hollow fiber module according to the present invention is manufactured by such a manufacturing method and is characterized by excellent quality.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to this.

  FIG. 2 is an image of the potting end face of the hollow fiber membrane module M taken by the imaging device 4. When the normalized correlation process is performed on the image by the model image shown in FIG. 5 in the hollow fiber membrane detection device 5, the hollow fiber membrane candidate whose correlation degree R exceeds the correlation degree threshold value Rt (0.5 in this example). Pixel coordinate information is obtained. The luminance average value A of the pixel group in the captured image having an area corresponding to the model image centered on this coordinate is obtained for each coordinate, and the upper limit threshold Atu (128 in this example) and the lower limit threshold Atl (this In the example, compared with 36), by extracting only those within the range, the coordinate information of the hollow fiber membrane candidates is narrowed down. Further, the luminance standard deviation σ of the pixel group in the captured image having an area corresponding to the model image centered on the coordinates is obtained for each coordinate, and an upper limit threshold σtu (32 in this example) and a lower limit threshold σtl (this In the example, compared with 5), the coordinate information of the hollow fiber membrane can be obtained by further narrowing down to only those within the range.

  When the mark 15 is plotted on the captured image based on the coordinate information, an image shown in FIG. 9 is obtained, and the number N of hollow fiber membranes detected from the number of the coordinate information is measured. In this example, the number N of detected hollow fiber membranes was 1378.

  Finally, as a result of comparing the detected number N of the hollow fiber membranes with the hollow fiber membrane number threshold Nt of the hollow fiber membrane module M (1662 in this example), the detected number N of the hollow fiber membranes is less than the threshold value Nt. The module M was determined to be defective and excluded from the manufacturing process.

It is a whole block diagram of the apparatus in one Embodiment of this invention. It is the image of the potting end surface imaged with the apparatus shown in FIG. Fig. 3 is an enlarged view of a part of the image shown in Fig. 2. It is the flow of a process in the hollow fiber membrane detection apparatus 5 shown in FIG. 5 is a model image of a normal yarn used in the normalized correlation process shown in FIG. It is an example including the image of the low-intensity part by the unevenness | corrugation 13 which generate | occur | produces on the image of the potting end surface shown in FIG. It is an example including the image of the low-intensity part by the crack 14 which generate | occur | produces in the potting end surface shown in FIG. It is the flow of a process in the defect determination apparatus 6 shown in FIG. It is the image which plotted the mark 15 with respect to the image shown in FIG. 2 about the hollow fiber membrane detection result by the hollow fiber membrane detection apparatus 5. FIG. In the apparatus shown in FIG. 1, it is a schematic diagram for showing the state of regular reflection when light from various light sources 3a is incident and the potting end face is warped or inclined. The calculation formula of the correlation degree R by the normalized correlation is shown.

Explanation of symbols

M: Hollow fiber membrane module 1: Module transfer device 2: Module support device 2a: Module support mechanism 2b: Module scanning mechanism 3: Light irradiation device 3a: Light source 3b: Power source 4: Imaging device 5: Hollow fiber membrane detection device 6 : Defect determination device 7: Operation command device 8: Display device 9: Module discharge device 10: Resin portion 11: Hollow fiber membrane portion 12: Hollow portion 13: Low luminance portion due to scratch 14: Low luminance portion due to unevenness 15: Hollow fiber Film detection mark R: Correlation degree by normalized correlation Rt: Correlation degree threshold A: Luminance average value Atu: Upper limit threshold of luminance average value Atu: Lower limit threshold of luminance average value σ: Luminance standard deviation σtu: Upper limit of luminance average value Threshold value σtu: Lower limit threshold value of luminance average value N: Number of detected hollow fiber membranes Nt: Number of detected hollow fiber membranes Threshold value θ: Warping of potting end face, angle of inclination θi: Potting end from light source 3a Incident angle θo of light irradiated onto the surface: emission angle of specularly reflected light from the potting end surface to the imaging device 4

Claims (3)

The potting end surface of the hollow fiber membrane module is irradiated with light from a planar light source that satisfies the condition of the following expression (1), and the reflected light from the end surface is imaged, and an image obtained by the imaging and a predetermined model image When the number of the hollow fiber membranes confirmed by the detection is below a predetermined hollow fiber membrane number threshold value, the hollow fiber membrane module is detected. A method for inspecting a hollow fiber membrane module, characterized in that it is determined as a defective product.
θ: Warping or inclination angle of potting end face of hollow fiber membrane module
H: Vertical and horizontal dimensions of flat light source (mm)
D: Distance (mm) between the optical axis center of the planar light source and the potting end surface of the hollow fiber membrane module The model image is a model image of a hollow fiber membrane having a hollow hollow portion, and the image has a region corresponding to the model image centered on a pixel group of the model image and each pixel of the image obtained by the imaging. The hollow part is detected as a hollow fiber membrane in a hollow state when the degree of correlation calculated by the normalized correlation with the pixel group in the inside is higher than a predetermined correlation degree threshold value. Inspection method for hollow fiber membrane module. A means for irradiating the potting end face of the hollow fiber membrane module with light including a planar light source that satisfies the condition of the following expression (2), a means for imaging the reflected light from the end face, and an image obtained by the imaging And means for detecting a hollow fiber membrane in which the hollow portion is in a hollow state by correlating the predetermined model image, and when the number of the hollow fiber membranes confirmed by the detection is below a predetermined hollow fiber membrane number threshold value An inspection apparatus for a hollow fiber membrane module, comprising means for determining the hollow fiber membrane module as a defective product.
θ: Warping or inclination angle of potting end face of hollow fiber membrane module
H: Vertical and horizontal dimensions of flat light source (mm)
D: Distance (mm) between the optical axis center of the planar light source and the potting end surface of the hollow fiber membrane module